Tamper-proof key-operated electric control station



March 5, 1968 R. J. BYOWMAN ETAL I 3,372,251

TAMPER-PROOF' KEYOPERATED ELECTRIC CONTROL STATION Filed Feb. 23, 1967 Q 48 Q 4 52 4e |6\ 58A 6O I28 a 36 36 I38 I28- ,94 I24 4 92 INVENTOR$ ROBERT J. BOWMAN DAVID EWESOLOWSKI United States Patent Ofitice 3,372,251 Patented Mar. 5, 1968 TAMPER-PROGF KEY-OPERATED ELECTRIC CONTROL STATION Robert J. Bowman and David F. Wesolowski, Milwaukee, Wis., assignors to Square D Company, Park Ridge, 11L, a corporation of Michigan Filed Feb. 23, 1967, Ser. No. 617,907 6 @laims. (Cl. 200-44) ABSTRACT F THE DISCLOSURE A key-operated tamper-proof electric control station having a die cast outlet box and cover with externally accessible screws securing the cover to the box. An internal locking arrangement provided for the control station includes a pin extending from one internal end wall of the box and a strike plate extending from the other internal Wall of the box prevents unauthorized access to switches carried by the cover when the securing screws are removed unless a key-operated lock, which actuates the switches and carries a member which hooks behind a portion of the strike plate, is rotated to an unlocked position.

switches frequently are installed in control stations to prevent inadvertent or unauthorized operation of equipment. When so used, the key-operated selector switches are provided with at least one locked position in which the key may be removed from the lock cylinder and at least one operative position which is achieved by rotating the key in the lock to actuate a switch within the control station. As the control stations may be subjected to adverse environmental conditions, die cast outlet boxes and covers are used and freely accessible screws are provided to secure the cover to the box.

A typical installation in which a control station incorporating the present invention may be used is in a control circuit for an electrically operated door wherein the control station is located in an area legally accessible to the public. Thus when screws are the sole means for maintaining the cover and outlet box assembled, all that is required for unauthorized entry through the door controlled by the control station is to remove the readily accessible screws to obtain access to the switches which control the operation of the door.

It is an object of the present invention to provide a key-operated selector switch control station with a locking cover assembly for the purpose of preventing unauthorized operation of the switches within the control station.

A further object is to provide an inexpensive and compact locking assembly for a cover of a key-operated control station which will require that a key-operated switch be actuated by the key before the cover for the control station can be removed.

An additional object is to prevent unauthorized removal of a cover from an outlet box of a key-operated control station that has at least one switch positioned between a cylinder lock carried by the cover and a rear wall of the outlet box to provide a compact arrangement in the control station and to rotate a member which locks the cover to the box to an unlocking position when the lock is operated by a removable key to an unlocking and switch operating condition.

Another object is to provide a tamper-proof key-operated control station, as may be used to operate a mechanism for opening and closing an entrance door in a building, with a locking assembly which will prevent removal of the cover for the control station when the freely accessible screws, which are used to secure the cover to the outlet box, are removed by an unauthorized person to prevent the actuation of the switches within the control station to obtain entry into the building without using a key and to provide the locking assembly with a pin and hole connection at one end of the cover and the box and a locking member at an end of the box opposite the one end. The locking member is formed to have a locking portion engaged by a member which is moved by the cylinder lock into a locking position with the locking member when the lock is in a locking condition to prevent removal of the cover from the box, and said locking member also having portions spaced from the locking portion that engage the inner surfaces of the cover to prevent rotation of the cover and disengagement of the member with the locking portion when the screws which are used to hold the cover in sealing engagement with the cover are removed and to provide the control station with an additional switch that is held against removal from an opening in the cover by a member extending from a mounting for the switches which are operated by the cylinder lock.

Further objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

FIG. 1 is a front plan view of a control station incorporating the locking assembly according to the present invention.

FIG. 2 is a sectional view generally taken along the line 22 in FIG. 1.

FIG. 3 is a rear view of the cover as detached from the electrical outlet box of the control station shown in FIG. 1.

FIG. 4 is a perspective view of a locking member shown in FIG. 2. v

While not limited thereto, the key-operated control station 10 as shown in the drawings is particularly suited for controlling the opening and closing of a garage door from an external switching station by authorized persons having a key. As the control station 10 may be exposed to deleterious atmospheric conditions, it is preferably provided with a die cast electrical outlet box 12 having an open front 14 exposing an internal cavity 16 extending between a top end wall 18 and a bottom end wall 20. The bottom end wall is provided with a suitable electrical fitting that is attached to a conduit enclosing electric conductors, also not shown. The open front 14 is closed by a detachable die cast cover 22 having a shape conforming to the external configuration of the open front 14. The cover 22 has a front face 24, a rear face 26 with suitably located openings 27 extending between the front face 24 and the rear face 26 at each corner of the cover 22 that are aligned with threaded openings in the box 12. The openings 27 and the threaded openings in the box 12 accept screws 28 to secure the cover 22 to the box 12. As shown, the heads of the screws 28 are readily accessible externally of the front face 24 of the cover 12 so the cover 12 may be easily removed to expose the internal components of the control station 10.

The rear face of the cover has a peripheral flange 32 surrounding a recess 34 as defined by vertical side walls 36. When the cover 22 is attached to the box 12 a seal 40, compressedbetween the flange 32 and an edge of the open 3 front 14; provides aweather-tight joint between the cover 22 and the box 12.

The cover 22 has two openings, not specifically shown, spaced along a vertical center-line of the cover 22, as in FIG. 1, which provide a passage for a barrel 42 of a mortise cylinder lock 44' and an operator 46 of a switch assembly 48. The switch assembly 48 may be of any commercially available type and, as shown, is fully disclosed in an application for US. Patent, Ser. No. 453,410, filed on May 5, 1965 and assigned by the inventors Merlin Y. Turnbull, Josef B. Bierenfeld and Carl B. Sohns to the assignee of the present invention. As disclosed, the operator 46 of the switch assembly 48 includes a" hollow sleeve, not'shown, extending through an opening in the cover 22. The sleeve has'a threaded exterior to which a ring nut 52 is applied to force a flange portion 54 on the sleeve toward the rear face 26. Positioned on the flange portion 54 is an adapter 56 which provides a support for a contact block assembly 58. Extending through the hollow sleeve is an operating button 60 having an outer end exposed to the front face 24 side of the control station and extending to engage a movable spring biased button, not shown, extending from the contact block assembly 58. The contact block assembly has movable contacts which open when the button 60 is pressed inwardly. Thus the switch assembly 48 including the button 60 may be used as a stop switch in the control station 10 for the purposes well known to those skilled in the art.

The mortise cylinder lock 44, also may be of any well known commercially available type, includes the barrel 42 which extends through a suitable opening in the cover 22. The barrel 42 has a flanged face 62 on one end which is tightly pressed against the front face 24 and is externally threaded so a hex nut 64 may be threaded thereon and secure a switch mounting bracket 66 and a spacer 68 against each other on the rear face 26. The barrel 42 has a plug 70 extending 'therethrough which is rotatable by a key 72 received in a suitable key slot at the front face 24 side of the control station. They key 72 is removable from the key slot when the plug 70 is in a locking position with the barrel 42. Secured on an end of the plug 70 on the rear face 26 side of the cover 22 externally of the barrel 42 is a member commonly known as a bolt 74 for the cylinder lock 44. The bolt 74 is moved whenever the plug 70 is rotated from a center locked position by the key 72 in either clockwise or counterclockwise direction. As shown in FIGS. 2 and 3, a pair of screws 76 are used to attach a locking and switch operating member 78 and the bolt 74 to the'end of the plug 70 so the member 78 moves with the bolt 74 upon rotation of the plug 70.

The'switch mounting bracket 66 is provided with a base portion 80 having a suitable opening therein to receive the barrel 42 so the base portion 80 is tightly secured between the hex nut 64 and the spacer 68 when the hex nut 64 is tightened to secure the barrel 42 to the cover 22. Extending outwardly along one edge of the base portion 80 is a switch mounting portion 82 that terminates in a pair of spaced ears 84 each of which has an opening therein. Positioned by the mounting portion 82 and the ears 84 on opposite sides of a center-line passing through the plug 70 are a pair of oppositely facing switches 86 and 88 each having an operating button 90 movable along an axis parallel to the rear face 26. The switches 86 and 88 are of the well known commercially available types and may be of the snap acting single pole-double throw type, having their internal parts arranged to bias the operating buttons 90 outwardly of the housing for the switches 86 and 88 and their contacts arranged to provide a set of normally open contacts which are closed when the buttons 90 are actuated and a set of normally closed contacts which open when the buttons 90 are actuated by being moved inwardly in the housings for the switches 86 and 88.

As shown in FIG. 3, the switch 86 is directly positioned against the ears 84 and the switch 88 is positioned by a pair of sleeves 92 which act as spacers to position the switch 88 on the ears 84 when nuts 94 are tightened on bolts 96 extending through suitable openings in the switches 86 and 88, the ears 84 and the sleeves 92. The mounting bracket 66 is formed to position the switches 86 and .88 between the rear face 26 and a bottom wall 98 of the box 12. Extending inwardly into the cavity 16 adjacent the open front 14 is a pin 100 that is secured to the top end wall 18. The pin 100 is arranged to receive an opening in a member 102 which acts as a hook to prevent the end of the cover 22 adjacent the end 18 from rotating relative to the box 12 and being detached from the box 12. The member 102 is provided with an apertured base portion 184 which surrounds the sleeve of operator 46 and is secured against the rear face 26 by the flange portion 54 when the ring nut 52 is tightened. The mounting portion 104 is maintained in position against the rear wall 26 by a flange portion 106 which engages a wall portion 36 of the cover 22 and has the opening therein which receives the pin 100.

Positioned adjacent the wall 20 within the cavity 16 is a strike plate 108 which is most clearly shown in FIG. 4A The strike plate 188 has a base portion 110 secured on the wall 20 by rivets which pass through openings 112 in the base portion 110. Centrally located along a front edge 114 of the base portion 110 is a portion 116 which extends to the rear of the open front 14 inwardly into the cavity 16 along an axis through centers of the plug 70 and the pin 100. The portion 116 acts as a locking portion of the strike plate 108, as will be later described.

Positioned on opposite sides of the locking portion 116 on the edge 114 are portions 118 and 120 which are spaced from the locking portion 116 to provide notches 122 and 124. The portions 118 and 120 each extend forwardly of the open front 14 and are arranged to engage the wall portions 36 of the cover 22 to prevent rotation of the end of the cover 22 adjacent the wall 20 relative to the box 12 when the screws 28 are removed.

It will be seen that unauthorized entry into the control station may be had by removing the ring nut 52 and forcing the switch assembly 48 inwardly into the cavity 16 to a position which will permit operation of the switches 86 and 88 while the cover 22 is in proper positionon the box 12. This result is defeated by a member 124 that has a mounting portion 126 secured to the mounting portion 82 of the switch mounting bracket 66 and a portion 128 engaging the rear surface of the adapter 56 to prevent movement of the switch assembly 48 into the cavity 16 when the nut 52 is removed.

The switch operating member 78 has a base portion 130 attached to the end of the plug 70 by the screws 76. Extending upwardly from the base portion 130 is a means for actuating the switches 86 and 88 which, as shown, includes a pin 132. The pin 132 extends vertically from the base portion 130 and is located to have a free end positioned out of engagement with the operating buttons 90 of both switches 86 and 88 when the plug 70 is positioned in the locking position in the barrel 42 so the key 72 may be removed. Thus when the key 72 is removed from the control station 10 neither of the switches 86 or 88 will be activated. The pin 132 is secured to the base 130 to have its free end movable in an arcuate path into engagement with the operating buttons 90 to actuate either of the switches 86 or 88 when the plug 70 is rotated from its locked position. Thus if the plug 70 is rotated in a counterclockwise direction, the pin 132 will be moved to actuate the switch 86 as shown in FIG. 3 and if the plug 70 is rotated in the opposite direction from its locking position, the pin 132 will actuate the switch 88. Extending outwardly from the base portion 130 is a latch means which is engageable with the locking portion 116. As shown in FIG. 2, the latch means is formed as a finger 134 having a portion 136 extending toward the rear face 26 to pass a free end 138 on the portion 116 with clearance. The finger 134 also has a portion 140 extending parallel to the rear face 26 which is positioned to engage a surface 142 on the portion 116 when the plug 70 is in a locking position. Thus an attempt to remove the cover 22 from the box 12 when the plug 70 is in a locking position will be defeated by locking action provided by the portion 140 as it engages the surface 142. The finger 134 has a width less than the width of the notches 122 and 124 to pass between the portions 118 and 116 or 120 and 116 with clearance when the finger 134 is removed in response to the movement of the plug 70. Thus the cover 22 is removable from the box 12 when the key 72 is used to rotate the plug 70 in either direction from its locked position to actuate the switches 86 and 88 and is secured to the box 12 when the plug 70 is in its locking position.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given the broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. In a tamper-proof control station having: an electrical outlet box having an open front, a pair of end walls and an internal cavity exposed by the open front and extending between the end walls, a cover shaped to close the open front, said cover having a rear wall facing the cavity, a front wall externally exposed when the cover is in a closing position with the open front, means externally accessible on the front wall for removably securing the cover to the box in the said closing position with the box, a switch and lock assembly carried by the cover to be positioned Within the cavity when the cover is in the closing position, said assembly comprising: a mortise cylinder lock having a barrel extending through an opening in the cover, a key-operated plug extending through the barrel, a key insertable in the plug, said plug being rotatable by the key from a locked position to at least one other position in the barrel, at least one switch within the cavity, a mounting for the switch carried by the barrel for positioning the switch between the cylinder lock and a rear wall of the cavity, means carried by the plug for actuating the switch upon rotation of the plug, and locking means preventing removal of the cover from the box independently of the externally accessible securing means, said locking means including; a hook and pin connection provided by a first of said pair of end walls of the box and an end of the cover adjacent the said one end wall of the box when the cover is in the closing posi tion, a strike plate carried by a second of said pair of end walls, said strike plate having a locking portion within the cavity and portions spaced on opposite sides of the locking portion engageable with portions of the rear wall of the cover for preventing rotation of the cover from the closing position and latch means carrier by the plug engageable with the locking portion when the plug is in the locking position for preventing removal of the cover from the closing position, said latch means being movable by the plug to a disengaged position with the locking portion when the plug is rotated to actuate the switch to permit removal of the cover from the closing position.

2. The combination as recited in claim 1 wherein the plug is rotatable from a latching position in opposite directions and the latch means is moved to be disengaged from the locking portion when the plug is rotated in either of said opposite directions.

3. The combination as recited in claim 1 wherein the hook and the pin connection is provided by a pin extending from the first end wall and a member immovably secured to the rear wall of the cover, said member having a flanged portion having an opening therein receiving the pin.

4. The combination as recited in claim 1 including a pair of switches carried by the mounting to be positioned between the bolt and rear Wall of the cavity, said pair of switches being carried by the mounting to face in opposite directions in the cavity and having linearly movable operating plungers in spaced relation to each other in a plane parallel to the rear wall of the cover and the means for actuating the switches includes a pin having an end carried by the plug and free end extending be tween the spaced plungers.

5. The combination as recited in claim 4 including a third switch positioned by a second opening in the cover, said third switch having an operating portion externally accessible on the front wall of the cover and an assembly positioned within the cavity when the cover is in the closing position, and a member carried by the mounting for the pair of switches, said member having a portion engageable with a portion of the assembly to prevent removal of the third switch from the second opening in the cover.

6. The combination as recited in claim 3 wherein the cover has a second opening therein including a push button switch having: an operating button portion extend ing through the second opening to be accessible on the front wall, an assembly including a switching mechanism in the cavity when the cover is in the closing position and the member having the flanged portion is secured to the rear wall by a portion of the switch assembly.

References Cited UNITED STATES PATENTS 1,554,048 9/1925 Thomas 200-42 1,667,018 4/1928 Vandevelde 200-168 1,949,806 3/1934 Miller 200168 2,544,761 3/1951 Kilminster 200-168 3,056,481 10/1962 Luenser 20042 X 3,179,761 4/1965 Malota et al 200-168 X ROBERT K. SCHAEFER, Primary Examiner. H. J. HOHAUSER, Assistant Examiner,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,372 ,251 March 5 1968 Robert J. Bowman et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 5, lines 8 and 9, for "removed" read moved llne S4, for "carrler" read carried Signed and sealed this 20th day of May 1969.

Commissioner of Patents (SEAL) Attest:

Edward M. Fletcher, Jr. Attesting Officer 

